In this game, you must protect your cities from incoming missiles by shooting them down with your own. To do this you must position your cross beneath an enemy missile and fire. A shot from one of your three missile bases will then detonate and, hopefully, destroy the enemy.
At the end of a wave, your bonuses are counted up and a new wave starts. On the second wave, planes and satellites fly across, dropping more missiles unless destroyed.
From wave 6 onwards, look out for diamond shaped "Smart" missiles, which avoid your explosions.
You can fire from either individual bases, or from the nearest base to your cross. The game can be played with either a joystick or using the keyboard.
This game was mentioned in the following articles: